Quantum computational advantage attested by nonlocal games with the cyclic cluster state

• Published in: arXiv.org
• Main Authors: Daniel, Austin K, Zhu, Yinyue, C Huerta Alderete, Buchemmavari, Vikas, Green, Alaina M, Nguyen, Nhung H, Thurtell, Tyler G, Zhao, Andrew, Linke, Norbert M, Miyake, Akimasa
• Format: Paper Journal Article
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 26.07.2022
• Subjects: Accuracy; Boolean algebra; Circuits; Clusters; Fault tolerance; Games; Physics - Quantum Physics; Quantum computers; Quantum computing; Qubits (quantum computing)
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.2110.04277

We propose a set of Bell-type nonlocal games that can be used to prove an unconditional quantum advantage in an objective and hardware-agnostic manner. In these games, the circuit depth needed to prepare a cyclic cluster state and measure a subset of its Pauli stabilizers on a quantum computer is compared to that of classical Boolean circuits with the same, nearest-neighboring gate connectivity. Using a circuit-based trapped-ion quantum computer, we prepare and measure a six-qubit cyclic cluster state with an overall fidelity of 60.6% and 66.4%, before and after correcting for measurement-readout errors, respectively. Our experimental results indicate that while this fidelity readily passes conventional (or depth-0) Bell bounds for local hidden-variable models, it is on the cusp of demonstrating a higher probability of success than what is possible by depth-1 classical circuits. Our games offer a practical and scalable set of quantitative benchmarks for quantum computers in the pre-fault-tolerant regime as the number of qubits available increases.